DuMont Television Network ID from 1950.
December 14, 2009
Dumont Mirror Flip
In the old days of TV, 1 movie projector and 2 slide projectors were positioned at 90 degree angles to each other and matrixed optically into one TV camera. To switch from a slide to a film or from slide to slide or from film to slide, a mirror was flipped that would redirect one image and block out the others. This was called a "mirror flip", and most TV stations and networks had a prohibition against flipping on the air. DuMont apparently didn't have that rule.